


Planters in Crime

by Opossumtivity



Category: Adventure Time
Genre: Adventure & Romance, Fluff, Other, gender neutral reader
Language: English
Status: In-Progress
Published: 2020-10-11
Updated: 2021-01-10
Packaged: 2021-03-07 21:28:57
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 4,356
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26944447
Author URL: https://archiveofourown.org/users/Opossumtivity/pseuds/Opossumtivity
Summary: Fern thought he would find answers about his identity and purpose from the Grass Wizard, however a mysterious witch offers him something similar... Or even better.
Relationships: Fern the Human/Reader
Comments: 3
Kudos: 22





	1. Chapter 1

**Author's Note:**

> Haha get it? It's like saying Partners in Crime... But with plants cause they're both... Okay I'll stop n.n'
> 
> Fern is refered to grass Finn in this chapter since he still doesn't rename himself yet.

What am I?

It's a question Fern has been asking himself since breaking out of the sword.

He's not Finn, that's for sure. Then what is he?

Jake is a lot of things, a past criminal, a party animal but most importantly a helpful brother when his younger bro is having problems. No matter if this Finn is made of grass, he's still Finn in away. After trying to find ways for the grass Finn to feel at home, Jake remembered a key aspect both Finn's share no matter the differences in biology.

"Do you know of any evil we can fight?" Jake asks him.

"Yeah, I think I know a place." The grass Finn trails off, visions and memories of grassy hills and odd enchantments plaguing his mind.

* * *

"Yeah... This isn't exactly what I had in mind." Jake grimaced slightly when the grass Finn unapologetically sliced through the harmless grass golem. The dude just wanted to recite a riddle!

Good grief.

Even the destruction the grass Finn left behind felt too much.

"Time, the answer was probably time right?" the grass adolescent turned around to look at Jake.

The magical dog could only tilt his head with an awkward smile.

If this is what makes him feel better, I won't interrupt. Jake kept telling himself.

But he couldn't stay quiet any further, especially when Grass Finn started brutally punching the already defeated wizard.

Jake's the adult here, he should get him to stop. But before he could suggest a different alternative for the grass wizard, his doggy ears perked up at the sound of footsteps behind him.

A cloaked figure made their way up the hill, a bent witch hat resting on their head and a long cloak that reached their knees. A witch apparently.

"Fiddlesticks," the stranger cursed upon noticing the beaten Grass Wizard. "Guess I'm not the only one who has beef with the grass wizard. What did he steal from you guys? Magic Recipes? Enchantments? Curses? "

"Uh..." Jake made eye contact with Grass Finn, but the witch interrupted before he could respond.

"You know what, forget it. Just leave him to me, I'll make sure to teach him a lesson." their voice lowered, indifferently walking past the dog.

The grass wizard raised his head, jumping in surprise upon recognizing the stranger.

"Ah, (y/n) I can explain!" the wizard begged, trying to crawl away.

"Shut it! I don't know how you wizards handle stealing, but in the witch community, it's a huge offense," you threaten the wizard, although your tone is calm there's still anger behind it.

Jake saw the witch's cloak shake before two leaf objects floated alongside the witch, the sun's reflection bouncing off the leaves almost like a metallic blade.

"Hey knock it off, both of you!" Jake calls out. "We're gonna do what's right and that that guy to a hospital. Isn't that right grass Finn?" Jake directed his attention to his brother.

"Beat someone up just to take them to a hospital? Yeah, smart move," you scoff sarcastically.

The Grass Finn eyed you suspiciously, letting go of the wizard but not actually moving from his spot.

"Step aside." the witch ordered.

But the Grass Finn remained reluctant.

"I was here first! If someone has a say on this old man, it's gonna be me." he stood his ground.

Jake bit his nails, feeling the tension of a fight starting to pick up.

"I'd be careful with him leaf witch, he can get quite rough," Jake warns you.

"Oh, I don't mind getting rough," you taunt. "Bring it on grassy boy!" 

One of the floating leaves suddenly shot towards Grass Finn, but the adolescent blocked it off with his own grass blade. The clinking of the leaf against his grass blade proves how sharp those leaves really are, maybe because of the magic blue glow around it

"Quick reflexes," you notice with a hum. "Good, but not enough."

The second leaf took aim for his unblocked side, twirling the blade at the right angle just to sent it flying away, but the leaf regains it's momentum and floated back to your side.

"Cut it you two already!" Jake tries to interrupt, but was thrown back by the grass Finn's vines.

He wanted to deal with you himself. 

Unlike the grass monsters from the maze you became a troubling opponent for the grass boy, keeping him on his toes as he struggles to block each leaf you threw at him, barely keeping a steady rhythm.

It's a challenge. But it's a challenge he welcomes.

While the grass boy struggled. You, however, didn't have to do much physical effort besides nod in the direction to shoot your leaves.

'Typical magic users.' Grass Finn thought. 'They're too dependent on their magic I bet they don't have any defenses, in fact...

The grass Finn sheaths his sword, for now, turning his fist into a huge spiky fist, heading straight for the leaf witch. He dodges the leaves you threw at him before jumping, throwing his fist back before dropping it on you.

"Finn don't!" Jake shouts worryingly, he doesn't want two people to end up at the hospital.

But you didn't move from your spot, leaving yourself open at the attack. Grass Finn had a triumphant grin on his face, but when his eyes met with yours, all you did was give him a knowing smile.

Jake was almost blown back by the aftermath, looking at the poor witch in grief, however his expression grew into one of surprise.

You're still standing in place, and in one piece.

Your cloak is gone, but in its place, a huge shield made of different leaves blocked the grass Finn's fist from reaching you.

"Alright, I've seen enough," the leaves retrieved back to you, forming the cloak around you.

"What?" the grass Finn fell back. "I thought I knocked you out already," he grumbles.

An amused chuckle erupted from your lips.

"You were close, but your anger got the best of you," you shake your head lightly. "Other than that, you're pretty strong and skillful. This might sound a bit bold, but I would like to have you as my familiar," you said in an amicable tone.

The grass Finn quirked an eyebrow at you. "A what now?"

"A familiar, it's like an assistant for witches or magic users. I could use a plant-like fellow as yourself to help me run some errands. In exchange for your service, I offer payment and even help you out with that temperament of yours," you explain.

"Bull stuff, I don't have a temperament!" he raises his voice.

"Right..." you look back at the wrecked grass maze. "Just in case, here's my contact info if you ever change your mind." a single leaf floats from your cloak and straight to grass Finn's direction.

The adolescent grabbed the invitation, noticing how it has dark words burnt into it.

Without anything left to say, you walk down the hill in tranquility, leaving behind the two brothers to handle the grass wizard. At least he had his lesson in the end.

"What was all that about?" the grass Finn asks Jake, to which the dog shrugs.

A pained groan came from the Grass Wizard, reminding the two of them he's still there. "I can't feel my leg-"

"Let's take him to the hospital first," Jake suggests.

Grass Finn complies, carrying the old geezer on his shoulder. His gaze lingers on the leaf in his hand before stuffing it inside his pocket. 


	2. Chapter 2

"From now on call me Fern, Fern the Human," the grass boy exclaims proudly.

Finn and Jake felt good for the plant boy wanting to pursue his own identity and such.

It wasn't until Startchy showed up a few seconds later, rocking a sweet new motorcycle cycle and black sunglasses to match. However, the candy person didn't get a shot to enjoy them for long as Fern approached him and pushed him off the vehicle.

"Sorry, Fern needs this," he apologized, but not really.

"Nooo, Startchy's midlife crisis!" he extends a hand to his lost bike.

"Fern wait!" Finn tried to stop him, but Jake just held his shoulder.

"Let him go, Finn, he needs this."

As Fern rides away into the sunset, he pulls back his hat to feel the evening breeze flow through his hair, scattering flower petals behind him.

**"Where are we going?"**

"We'll be visiting someone,"

Fern stuck a hand inside his pocket, pulling out a leaf from his shorts.

* * *

The card didn't have an address in it, simply leading to a river passing by the pine forest east of Ooo

Fern was somewhat disappointed, it's not even dangerous or filled with magic. Just a normal river.

Fern parked his bike with a sigh as he sat on a log, tapping his fingers against the wood as he closes his eyes. The only sounds he can hear are the water currents, the chirp of birds, and the buzz of the occasional insect flying past his ear.

**"Growing impatient are we?"**

The grass boy groans in annoyance at the voice.

"I just don't want to waste my time, that's all," Fern replies.

 **"Last time I checked we had a free agenda,"** the grass demon chuckles within his head.

"Shut up,"

Fern whipped his head to the side, hearing something rustle between the bushes. The adolescent stood on his split feet, branding a sword in hand.

A familiar pointy hat emerged from the bushes.

"Oh, you came. I wasn't expecting to find you here so soon," you said with a surprised look on your face, before reverting back to a neutral expression.

"Why is that?"

"People normally don't get excited about being involved with witches," you shrug.

Walking past the grass boy with your buckets in tow, kneeling at the edge of the river to fill them up.

"Well, here I am, where do we start? dance around fire pits? turning people into frogs?" he jests.

You give the young man a look, lowering the buckets on the ground.

"Alrighty, though I need to make sure you won't steal my research notes so I'll be testing you,"

"What kind of test?"

You answer by pushing him into the river. Catching Fern by surprise and falling in the water with a high pitched yelp.

"Yo, what the flip?" he shouts, swimming against the current.

A snicker escapes your lips, cupping your hands around your mouth as the grass boy drifts further from the shore. "Be careful and try not to get pricked by the giant eel's spikes, I need the poison intact,"

"The WHAT?!"

Even if you explain it's not like Fern would be able to hear you. The grass boy felt something bite his ankle and drag him underwater, facing a giant eel-like you mention. Fern puffed his cheeks as he tries to hold his breath while kicking the eel's face with his other leg but it wouldn't let him go, to counter this the eels start swimming in circles in an attempt to dizzy Fern. Unable to use his fists, Fern summoned the grass blade in his hand and jab it in the eel's eye, releasing his ankle with a pained cry.

Instead of finishing the job Fern makes an attempt to reach the surface, realizing he won't last another minute without oxygen.

The eel recovered fast, spotting Fern with its single eye and smacking him downwards with its tail. Fern accidentally opens his mouth in surprise, immediately covering it with his hands.

Realizing he won't go anywhere with the eel in tow, Fern prepared his sword once more as the eel swims towards him with an open jaw. It's a terrifying sight but once it's close enough Fern stabs it in the other eye. He now has to choose between swimming upwards or the eel spikes.

The eel is now flailing like mad, but Fern grabs onto its body and climbs over its long slimy body. Upon feeling the intrusion, the eel bucks upwards like a wild horse and slaps Fern with its tail, sending the boy flying.

All the meanwhile, you patiently observe him from the edge of the river shore and even stepping aside as Fern crash lands on the ground.

"Did you get the spike?" you ask nonchalantly.

"Yeah, yeah I did," Fern rolls on his back, heaving on the shore as he raised his arm.

You snatch the spike from his hand, holding onto the item with the protection of your gloved hands. "Hm, it's small but it'll do," Fern heard you mumble.

"A warning would've been helpful, I could've drowned!" The grass boy snapped angrily at your relaxed attitude.

You look rather unfazed by Fern's angry tone, keeping your eyes glued to the poisonous spike. "I don't think so, I'm pretty sure grass people don't need to breathe,"

Fern opened his mouth to retort but immediately closed it since you're right.

That's why he can't play the flute after all.

"How did I do with your stupid test anyway?"

You eye him in amusement, "I found it interesting that you worried about drowning and being poisoned despite your grass body, you could've finished much quicker if you didn't worry about losing your breath," you carefully wrap the spike with a palm tree leaf as you reached a conclusion. "You behave like a normal human boy, and that held you back."

Fern frowned at the information, mostly because he was and is convinced he's still a human.

"Did I pass or not?" he grumbles, shaking the water from his hat.

You chuckle. "Almost, just one more thing. A riddle, easy as that,"

Fern groans in dismay. "I hate riddles..."

"What is something you keep after giving it to someone else?" you questioned.

The grass boy tapped a finger to his chin. "Uh, time?"

You shake your head with a laugh. "I'll give you the end of the day to figure it out," you said. After leaving your water buckets unattended, you went to pick them up with a stick, balancing them on either side of your shoulders Mulan style. "I'll be back in 10 minutes, in the meantime, I need you to watch over this," you toss him a rectangular item.

Fern barely caught it in his hands, flipping it over to reveal it's a notebook.

"What's this, your diary?" he jokes.

"Nope, it's where I keep all my research notes. It's very important to me and I don't wanna risk it getting wet," you explain. "I need you to watch over it until I get back, think you can do something as simple as that grassy boy?" you taunt.

"Better than you can leafily witch," he replies just as playful.

"Alright, just don't peak inside it. It has a wax seal and I'll know if you did," you warn in a stern tone before leaving.

"Easy peasy lemon squeezy."

And with that you head off into the pine forest, leaving Fern alone with your notebook and his thoughts.

**"What kind of magic writings do you think they have in there?" the demon wonders.**

Oh right, there's also the demon.

"Beats me, probably how to make bat juice or something," Fern shrugs uninterested, toying with the notebook. Although it's small it's still rather thick, with yellow pages bind together by a worn-out leather cover.

**"Hehe silly boy, witches are good with curses and hexes. Similar to the one with the grass blade,"**

Fern viewed the notebook in a different light.

What if you're the type who makes curses like the grass wizard? You said he stole spells from you, so what if...?

A ruffle came from the treetops, pulling Fern's attention from the notebook.

"I recognize you, you're the jerkwad who ruined the wizard battle a few years ago," A monotonous feminine voice spoke out, belonging to a face that pops out from the foliage. "Are you working with that witch?"

"Maybe I am or maybe I'm not, what about it?"

Huntress Wizard dropped from the tree top, gracefully landing on her feet with a crouch before walking towards Fern. "They're scheming critters within the magic-user community, definitely not trustworthy at all," she shakes her head.

Her cat-like eyes fall on the notebook in Fern's hands. "Is that where they keep their magic recipes? I can't believe they handed it to you so quickly," she asks in amazement.

"It's nothing," Fern says carefully, hiding it behind his back.

"Oh boy that's more than nothing," Hw shakes her head. "Look man I'll cut you a deal, hand me that notebook and I'll pay you twice as much as that witch did."

Fern looks away, expecting you to come back any second.

Hw takes his silence as uncertainty. "They'll probably use it for evil anyway, if you hand it to me I'll keep it safe,"

Even though the explanation made sense, Fern is incapable of handing over your notebook. Most witches he's met have indeed been evil like Maja or morally ambiguous like the garden witch, but this is something private that belongs to you, a chivalry part of him he can't break. Almost like a promise.

Fern gasps as he understands your riddle.

Huntress Wizard gave him an impatient look.

"Sorry lady, I can't give this to you," Fern shook his head. "Knight's honor," he bumps his hand against his chest.

The wizard took a step forward, unhappy with Fern's cooperation. "Hand it over grass boy, or I'll rip it from your tattered grass hands,"

Fern jumped up, fists up and ready. "Oh yeah? well, you'll have to rip it from my cold dead... oh right you already said that,"

Before Huntress Wizard could attack Fern, she jumped back to avoid a few sharp leaves embedded on the ground.

"Trying to steal my notes again Hw?" you walk up from behind a tree, listening to the whole ruckus.

Huntress Wizard only gave you an annoyed huff, combining herself with the forest floor and rushing out of the area.

You turn around to look at Fern, handing you your notebook safe and sound.

"I could've handled her myself," he states, puffing his chest.

"Yeah right," You chuckle at his display of bravery. "I'm happy with how you acted back there though, I guess you are trustworthy after all." you compliment him.

Fern felt good with himself. The same pleasant feeling he gets when he helps someone in need, you probably didn't need help, but knowing he did the right thing was enough.

"Did you solve my riddle by any chance?" you ask.

"I did, the answer is a promise,"

You nod at his answer, giving his shoulder a light bump. "Meet me here at 8am, we'll start tomorrow morning." and with that, you head off without him.

 **"Congrats Fern~"** the demon muses.

* * *

On your way back home you stumble into Huntress Wizard once more, but this time she's relaxed and friendly.

"Do you need me for anything else or are we done here?" she asks.

"Nope, you're free to go."

"Congrats on your new familiar, he seems... trustworthy," the wizard approves. "Don't tell me you seriously handed him your notes? would've made me kinda jealous (y/n)." Hw jokes.

"Of course not! all I have in here is my to-do list and grocery list," you laugh, waving the small notebook in your hand. "Just needed to make sure he won't backstab me."


	3. Chapter 3

Fern's footsteps are cautious and slow, his body tensed up and prepared for anything that you could potentially throw at him.

You suppress a chuckle in your throat. "Why are you walking like that?"

Fern didn't break eye contact from his surroundings, answering with a short breath. "I'm being cautious-"

"Of what exactly?"

"I dunno, anything coming from you,"

You shake your head, "Fern it was just one test, no need for the whole paranoia."

There's a mountain at the center of the pine forest. It isn't too big or too spectacular but the pools of spring water at the top is what makes it worth the visit. Especially for you, a witch without a proper cauldron.

"Why not just buy one?" Fern asks. Holding a bag of ingredients while the two of you trek up the mountainside.

"Because they're expensive as heck! Buying decent ingredients is enough of a struggle," you pat the side of your empty pockets. "These pools are useful for now."

Fern took a moment to appreciate the view from the mountain top. There's a light layer of snow powered over short mint-colored grass, little to no pine trees but the different sized pools compensate for the lack of plant life. He doesn't like snow, but he admits it's a neat view.

You however went straight to a specific pool, about the size of a regular bathroom sink. Fern notices the random items surrounding the pool edge, mostly mischievous things like dried fruits, used pots, mixers, and even some empty candy wrappers. Judging by the sleeping bag and the burnt firewood, it's easy to tell you camped here before.

Fern curiously walks up to the pool in front of your camp, leaning forward so he can get a better look at the boiling water. "Are these things boiling?"

"Yup! The mountain we're standing on is an active volcano that heats up pools left by the rain. Since it's constantly boiling I can use them without-"

"So you're using these instead of buying a pot?"

"...Pretty much, yes," you admit sheepishly.

"Glob, you're such a cheapskate." Fern cracks up a little at the detail. And to think this is the same with that he couldn't defeat back then.

"Whatever," he shrugs off, lowering the bag to the ground and sitting next to it. "What are we cooking here?"

"Patience, we're cooking patience," you hum, grabbing stuff from the bag.

Fern raised an eyebrow at you, you can already tell what he's thinking with that look of his.

"Okay, it's a surprise. I've been working on this for a while, all we gotta do is wait until it's done and you'll see," you grab a large spoon from the bag, stirring it inside the pool.

Upon closer look Fern notices bundles of... something. But he can't identify what it is without getting one-degree burns. The grass boy rests his chin on his closed hand, sighing in boredom. "Fine," he groans. "You're the boss here, if you wanna pay me for doing nothing that's your loss."  
At first, only minutes ticked by, but then they became hours. Eventually boring out Fern.

"This is boring," he sighs, rolling on his back. "At this rate, I'd prefer you'd toss me in the river again."

You casually flip the page of your book, only sparing a quick glance at Fern and the bubbling pool in front of you.

"There are no rivers here, but you can suit yourself one of these pools." you joke, but Fern remains quiet. Seriously considering your suggestion.

A few minutes pass, where at some point you raised your view from the spellbook and find out your assistant is nowhere to be seen.

"Fern?" you call out, eventually seeing a green hand poke out from one of the thermal pools at the edge of the center. You huff, unsure if you wanna separate from your boiling broth.

"What are you doing?" you inquire, placing your hands on your waist as you walk up to the young man.

"What does it look like I'm doing? I'm taking a break, these are thermal springs after all." Fern stretches his arms behind his head, "Come on in, the water is tolerable away from the center. The both of us could use a break."

You look back at your improvised pot with uncertainty. But the thought of relaxing your tense muscles sounded promising.

"Alright, I'll give in," you toss your hands in the air.

Unlike Fern, you just remove your boots and your socks, rolling up the bottom portion of your pants up to your knees, and take a seat at the edge of the pool. Your feet feel both warm and refreshed with the bubbling sensation, contently swinging your legs in the water.

"Just your feet?" a look of slight disappointment sprinkled on his face.

"Yeah, I'm still busy remember," you pause midway, giving him a sly look. "Why the disappointed look? you wanted me to remove my shirt like you?"

Fern looked away, scratching the base of his nose. "Whatever."

A dinging noise starts breaking through the mountain silence, sounding oddly familiar to an oven bell. Fern turns his head both ways to find the source, able to pinpoint its close by.

"It's finished!"

"Huh?"

You scramble to your feet in a hurry before Fern could ask what's the big deal, noticing you even left your shoes behind. Since he didn't wanna be left behind, Fern got out from the pool and grabbed your shoes, heading back to your makeshift camp in a light jog.

"Where's the fire?" he jests.

"Right here," you move to the object you held between a pair of metal tweezers, like the kind used for bbq. It's a hat, drenched and dripping with water, he can tell it's partially made of wood and the bottom portion of a mushroom with little leaves poking from the tree part.

"A hat?" Fern tosses your shoes at your feet.

"Not just a normal hat, it's a new witch hat!" you try to hold back the need to jump around like a happy bunny. "Been brewing this bad boy for weeks, I was worried it wouldn't be ready on time. But now I can't wait to test it out." you blow the steam away, hoping to hold it in your hands.

This made Fern nervous, especially if it meant he's gonna be target practice or not. "Oh nonono, you can pay me as much as you want but I'm not your guinea pig for your weird magic soup hat."

You shake an index finger at him. "Don't worry you're not gonna be my test subject," there's wickedness hiding behind your grin, almost shaking in excitement. "That's what the Wizard Battle is for."

**Author's Note:**

> I'll be taking a break from my one piece content to focus on this multi-chapter story.   
> What to expect:  
> \- Fern development with his grass demon  
> \- Censored curse words (example, "Flip what the zip)   
> \- Safe content (only the occasional dirty joke here and there like in the show)   
> \- A little bit of world building with the magic users  
> \- Canon Divergence
> 
> Updates will be every weekend. Other than that, let me know what you think in the comments~ <3


End file.
